Plasmid-mediated resistance to tetracyclines among strains isolated in Poland between 2012 and 2013.

INTRODUCTION

One of two main mechanisms of resistance in tetracycline-resistant (TRNG) is associated with the presence of TetM protein responsible for actively blocking of the tetracycline target site in the 30S ribosomal subunit. This mechanism is encoded by conjugative plasmids. The second mechanism is chromosomal in nature and due to mutations in specific genes.

AIM

To determine the incidence and type of determinants in TRNG strains isolated from patients presenting with gonorrhea infection to the Dermatology and Venereology Clinic in Warsaw in 2012-2013.

MATERIAL AND METHODS

Tetracycline and doxycycline susceptibility was determined by E-Tests. The presence and type of the gene were determined by polymerase chain reaction.

RESULTS

Tetracycline resistance was detected in 50.8% of the evaluated strains. The TRNG strains containing the plasmid constituted 13.8% of all the evaluated strains. Dutch type constituted 12.3% and American type 1.5% of all the evaluated strains. In the remaining TRNG strains, resistance to tetracyclines was presumably chromosome-encoded. The minimal inhibitory concentration (MIC) of tetracycline ranged from 0.25 to 32.0 mg/l, MIC = 2.0 mg/l, MIC = 32.0 mg/l. The MIC of doxycycline ranged from 0.25 to 32.0 mg/l, MIC = 4.0 mg/l, MIC = 16.0 mg/l.

CONCLUSIONS

Unlike most of European countries, in 2012-2013 in Poland, the Dutch type was found to be much more common than the American type. Minimal inhibitory concentration values of tetracycline and doxycycline were similar, with doxycycline exhibiting a somewhat lower effectiveness than tetracycline towards chromosome-mediated tetracycline resistant strains of .